Latching mechanism for electric switches



April 1947. w. G. HARLOW 2,418, 70

LATCHING MECHANISM FOR ELECTRIC SWITCHES Filed July 27, 1945 Inventor: Winoon G. Harlow,

10 3 His Attorne g.

Patented Apr. 8, 1947 LATCHING MECHANISM FOR ELECTRIC SWITCHES Winton G. Harlow, Upper Darby, Pa., assignor to General Electric Comp York any, a corporation of New Application July 27, 1945, Serial No. 607,371

9 Claims. (01. 200169) -My invention relates to improvements in latching mechanisms for electric switches and more particularly switches which are used to isolate or disconnect electric apparatus from the source of power. Such switches are known to the art as disconnecting switches, knife switches and the like.

Such switches often have to conduct large currents especially when overloads or faults occur on the circuit with which the switches are associated. The high magnetic stresses consequent upon the loop expansion effect tend to open the switches. Also, when such switches are used on warcraft and the like, shocks due to explosions, gunfire, etc. tend to open the switches. Inasmuch as such switches are not intended to interrupt the circuit during overload or fault conditions, it is necessary to prevent their opening under the action of both magnetic stresses and shocks and particularly so on warcraft since both are likely to occur simultaneously. Moreover, the interruption of a circuit by a switch under such conditions, even if the switch were not seriously damaged or destroyed, might well prove disastrous during battle conditions. Also, switches in the open circuit position may be undesirably closed in consequence of shocks, force of gravity, etc. In order to prevent such undesirable opening and closing of these switches, many latching mechanisms for holding the switch conducting members in the closed or open circuit position have been devised. Some of these have con unsatisfactory, others are limited in their application, and still others would not hold the switch conducting members in the open or closed circuit positions under shocks.

An object of my invention is to provide for isolating switches an improved latching mechanism which will positively hold the movable conducting members of the switch in one or more desired circuit controlling positions against the efiects of shocks, gravity and magneticstresses. Another object of my invention is to provide a latching mechanism which is equally applicable to single or double throw switches without change inthe switch structure itself. A further object of my invention is to provide a latching mechanism which is relativelysimple and easy to operate and economicalto manufacture. These and other objects of my'invention will appear in more detail hereinafter.

-In accordance with my invention, I provide for an isolating switch a dynamically balanced latching member which is biased to latching engagement with an opening in the handle mounted on the free ends of the movable switch conducting members. Also in accordance with my invention, I provide an element movably positioned in th opening in the switch handle for releasing the latching member under pressure of the operators fingers on a release bar slidably mounted in a recess in the switch handle. Further in accordance with my invention, I provide a latching mechanism which is readily applicable without change in switch structure to either a single or a double throw switch or to a single throw switch which is to be held in both the circuit open and circuit closed positions.

My invention will be better understood from thefollowing description when considered'in connection with the accompanying drawing, and its scope willbe pointed out in theappended claims. In the accompanying drawing, Fig. 1 illustrates a vertical front elevation of a double pole, single throw switch provided witha latching mecha nism embodying my invention; Fig. 2 is a side elevation of the switch shown in Fig. 1; Fig. 3 is a sectional elevation onthe line 33 ofjliig. 1 to an enlarged scale showing the latching mechanism in the latched position; and'Fig. 4 is a sectional elevation similar to Fi 3 showing the latching mechanism in the released position."

In Figs. 1 and 2, I have shown, .for the purpose of illustrating my invention, an isolating switch of the disconnecting or knife blade type comprising at least two spaced conducting elements l pivotally mounted on ,a base ,2 of in-jsulating material ,asflat 3 and '4 on suitable hinge studs5 for movement about acommon axis. ,As shown, each conducting element comprises two parallel blade members ,6, which in the closed cir-' cuit position embrace contact studs 1. In .order to insure firm contact between the blades 6" and the stud I especially under shock conditions,

the blades are resiliently interconnected adjacent .,the,studby suitable means such as abolt 6 passingthrough spring washers TI in engagement with the blades. For manually actuating the blades 1 to and from the circuitclosed position, their free ends are suitably secured to a handle .8 .provided with a longitudinal finger channels and thumb channels IEL, 'Forfbetter gripping, these channels maybe ribbed, asshown. For holding theblades I in one or more predetermined circuit controlling positions, I provide .a .latching mechanism which, as shown, comprises a bushing. .mounted .in the handle 8 transversely .thereo'fand provided witha liongitudinal opening l2. The bushing ll may be screwed into the handle 8, as shown. Cooperat ing with the bushing II is a latching member I3 which is adapted for latching engagement in the opening l2 in the bushing. Thus, for example, the latching member I3 is provided with a projection such as a cylindrical boss M which fits into the opening I2, as shown in Fig.3.

Further in accordance with my invention, I provide means adapted to be mounted on the switch base 2 for pivotally supporting the latching member IS in a position to cause latching engagement of the boss l4 and the bushing II when the blades are moved to a predetermined position. As shown, this means comprises a U- shaped member IS, the base of which is welded or otherwise suitably secured to a threaded post IS. The sides I! of the member I5 may be provided with lugs l8 which project into suitable openings l9 in the base to prevent turning, and a nut 20 and suitable washers 2|, one of which is a lock washer, serve to maintain the latch sup-- porting means in position. Between the sides of the U-shaped member I5 there is mounted a pivot 22 for the latching member I3 and around this pivot there is mounted suitable biasing means such as a looped torsion spring 23 which biases the latching member l3 to the latching position shown in Fig. 3. For shock-proof purposes, the latching member I3 is pivotally supported at its center of gravity whereby to obtain dynamical balance about its pivotal aXis 22. For this purpose, the lower end of the latching member i3 is extended and provided with counterweighting portions 24.

For limiting the rotation of the latching member in, the latch engaging direction, counterclockwise as viewed in Figs. 3 and 4, the pivot 22 may be positioned as shown so that the extension of thelatching'member bears against the supporting post l6 as shown in Fig. 3. Further in order. to stop the blades lrin a predetermined position such as to secure the desired latching engagement, I mount between the sides I! of the U-shaped member I 5 a stop 25 against which the handle, 8 comes to rest in the ,closed position of the switch as shown in Fig. 3. In the illustrated embodiment of my invention, the stop 25 also serves as an abutment for the looped end of the spring 23. If it" is desired to latch the switch blades l in both the open and closed positions, thentwo latching members I3'and the supports therefor are mounted'on the base, one on each sideof'the pivotal axis of the bladesas shown in Figsjl, and 2; Similarly, for a double throw switch, one latching member l3 and its support are providedffor each throw of the switch.

For releasing the latching member l3 from latching engagement with the bushing H in the normal process of gripping the handle' 8 to open theswitch, this handle is provided with a longitudinal recess 26' for, the reception of a latchreleasing bar21. This bar is rigidly secured to a plunger 28 whichismovably mounted in the path ofmovement of the latching projection M in a portion ofreduced diameter of the longitudinal opening l2 in the bushing H. The releasing bar 211s preferably long enough so as to be en- 'gageable by more than one finger in order that the "operator can readily release the latching member l3 without hunting for the end of the plunger 28 to press down with the right finger. Also'in order to prevent escape of the releasing bar, and-turning thereof, it is of a similar configuration as the recess 26 in the handle and the whichfits the latch receiving portion'of the bushing opening [2. The releasing bar 21 is suitably secured to the plunger 28 at the other end at such a distance. from the plunger head 29 that the bar 21 cannot escape from its recess and yet is still convenient for finger pressure to release the latching member. For easy engagement of the projection M in the opening l2 in the bushing H, the outer surface 30 of that portion of the bushing which is engaged by the projection l4 near the end of the blade movement is preferably beveled as shown whereby to move the latching member 13 clockwise, as viewed in Figs. 3 and 4, against the bias thereon.

'Assuming now that the switch is closed as shown in Figs. 1 and 2, then upon placing the fingers in the finger channel 9 of the handle 8 and pressing inwardly on the release bar 21, it will be apparent that the plunger 28 is moved from the left to right, as viewed in Fig. 3, to move the latch engaging member l3 from the latching position shown in Fig. 3 to the released position shown in Fig. 4. When the latch engaging member I3 is in the released position, a pull on'the handle 9 opens the switch. The switch may be then swung around into its other position, the lower position as shown in Figs. 1 and 2, whereupon the latch engaging member in the lower position will enter the opening l2 in the bushing II to latch the switch in such other position.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangement shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United'States is:

.1. In a latching mechanism for a'switch having at least two spaced conducting elements piv otally mounted on a base, a handle secured to the free ends of said conducting elements, a bushing mounted in the handle transversely thereof and provided with a longitudinal opening, a latching member adapted for latching engagement in the opening in said bushing, means adaptedto be mounted on the switch base'for pivotally supporting said latching member in a position to cause latching engagement'of the member and said bushing when said elements are moved toa predetermined position, and means adapted to be operated to disengage said member fromlatching engagement with said bushing comprising a plunger movably mounted in the opening in the bushing and engageable with the latching member for release thereof upon movement of the plunger in one direction.

2. In a latching'mechanism for a switch having at least two spaced conducting elements pivotally, mounted on a base, a handle secured to the free ends of said conductor elements, a bushing mounted in the handle transversely thereof and provided with a longitudinal opening, a latching member adapted for latching engage ment in the opening in said bushing, means adapted to be mounted on th8',SWll7Ch base for pivotally supporting said latching member ina position to cause latching engagement of the member and said bushing when said elements are moved to a predetermined position including means for stopping the elements in said position, and means adapted to be operated'to-disengage said member from latching engagement with said bushing comprising a plunger movably'mounted in the opening in the bushing and engageable with the latching member for release thereof upon movement of the plunger in one direction.

3. In a latching mechanism for a switch having at least two spaced conducting elements pivotally mounted on a base, a handle secured to the free ends of said conductor elements, a bushing mounted in the handle transversely thereof and provided with a longitudinal opening, a latching member provided with a projection for latching engagement in the opening in said bushing, means adapted to be mounted on the switch base for pivotally supporting said latching member in a position to cause latching engagement of said projection and said bushing when said elements are moved to a predetermined position, and means adapted to be operated to move said projection out of the opening in said bushing comprising a plunger movably mounted in the opening in the bushing and having one end engageable with the projection on the latching member for release thereof upon movement of the plunger in one direction.

4. In a latching mechanism for a switch having at least two spaced blades pivotally supported on a base for movement about a common axis, a handle secured to the free ends of the blades, a bushing mounted in said handle transversely thereof intermediate said blades and provided with a longitudinal opening, a latching member provided with a projection for latching engagement in the opening in said bushing, means adapted to be mounted on the switch base for pivotally supporting said latch ng member in a position to cause latching engagement of said projection and said bushing when the blades are moved to a predetermined position including means for stopping the blades in said position and means for biasing the latching member into latching engagement with the bushing, and means adapted to be operated to move said projection out of the opening in said bushing comprising a plunger movably mounted in the opening in the bushing and having one end engageable with the projection on said latching member for release thereof upon movement of the plunger in one direction.

5. In a latching mechanism for a switch having at least two spaced conducting elements piv otally mounted on a base, a handle secured to the free ends of said conductor elements and having a longitudinal finger channel provided with a longitudinal recess, a bushing extending transversely into the handle substantially midway of the recess therein and provided with a longitudinal opening, a latching member provided with a projection for latching engagement in the opening in said bushing, means adapted to be mounted on the switch base for pivotally supporting said latching member in a position to cause latching engagement of said projection and said bushing when the blades are moved to a predetermined position, means adapted to be operated to move said projection out of the opening in said bushing comprising a plunger movably mounted in the opening in the bushing and having one end provided with a releasing bar shaped to fit the recess in said handle and positioned in such recess for a limited movement substantially only transversely of the handle, the other end of said plunger being engageable with the projection on the latching member for release thereof upon movement of the releasing bar toward the bottom of the recess in the handle.

6. In a latching mechanism for a switch having at least two spaced conducting elements pivotally mounted on a base, a handle secured "to the free ends of said conductor elements, a; bushiing mounted in the handle transversely thereof and provided with a longitudinal opening, a latching member adapted for latching engagement in the opening in said bushing, means adaptedto be mounted on the switch base for pivotally supporting said latching member in a position to cause latching engagement of the member and said bushing when the blades are moved to a predetermined position including means for stopping the blades in said position, an inclined surface on said bushing engageable with said latching member to move the latching member against the bias thereon as the blades are moved to said predetermined position, and means adapted to be operated to disengage said member from latching engagement with said bushing comprising a plunger movably mounted in the opening in the bushing and engageable with the latching member for release thereof upon movement of the plunger in one direction.

'7. In a latching mechanism for a switch having at least two spaced blades pivotally supported on a base for movement about a common axis, a handle secured to the free ends of the blades, a bushing mounted in said handle transversely thereof intermediate said blades and provided with a longitudinal open ng, a latching member provided with a projection for latching engagement in the opening in said bushing, means adapted to be mounted on the switch base for pivotally' supporting said latching member in a position to cause latching engagement of said projection and said bushing when the blades are moved to a predetermined position including means for stopping the blades in said position and means for biasing the latching member into latching engagement with the bushing, an inclined face on said bushing engageable with said projection for moving said latching member against the bias thereon as the blades are moved to said predetermined position, and means adapted to be operated to move said projection out of the opening in said bushing comprising a plunger movably mounted in the opening in the bushing and having one end engageable with the projection on said latching member for release thereof upon movement of the plunger in one direction.

8. In a latching mechanism for a switch having conducting elements pivotally mounted on. a base, a handle secured to the free ends of said elements and provided with a transverse opening, a latching member adapted for latching engagement in the opening in said handle, means adapted to be mounted on the switch base for pivotally supporting said latching member in a position to cause latching engagement'of the member and said handle when said elements are moved to a predetermined position, and means adapted to be operated to disengage said member from latching engagement with said handle comprising a plunger slidably positioned in theropening in said handle and engageable with the latching member for release thereof upon movement of the plunger in one direction.

9. In a latching mechanism for a switch having conducting elements pivotally mounted on a base, a handle secured to the free ends of said elements, said handle having a longitudinal finger channel provided with a longitudinal recess and a transverse opening connecting with said recess, a latching member adapted for latching engagement in the opening in said handle, means adapted to be mounted on the switch base for ing a plunger slidably positioned in the transverse opening in the bushing and having one end engageable with the latching member and the other end provided with a releasing bar shaped to fit the recess in said handle and positioned in such recess for limited movement'substantially only transversely of the handle.

WINTON G. HARLOW. 

